Many diseases arise from the growth and spread of microorganisms that can affect all aspects of life, from human health, to animal health, to food and water safety, to the safety of the environments we live in. Disinfectants have found wide spread application in all these areas. Hospitals perform rigorous programs to disinfect and sterilize their environments. Consumer homes are replete with disinfectant hand cleaners, sprays, hard surface cleaners, disinfectant wipes, and fruit and vegetable washes. Disinfectants are widely used on farms where the difference between healthy and sick animals can mean the difference between profitability and loss.
Mastitis is one of the most common and economically costly diseases confronting milk producers. Economic losses result from poorer milk quality, lower milk production, and potential culling of chronically infected animals. The use of disinfectant solutions both before and after milking has found great success in preventing mastitis, particularly disinfectants based on acidified chlorite such as those commercially available from Alcide Corporation (Redmond, Wash.) and Ecolab Inc. (St. Paul, Minn.), and disclosed in U.S. Pat. Nos. 6,524,624, and 6,699,510.
Acidified chlorite (AC) disinfectants are commonly used as two-part products having a first part containing a chlorite (such as sodium chlorite) and a second part containing an acid. The AC disinfectant is formed upon mixing the first and second parts, and typically only in amounts sufficient for a given use period. Depending upon the desired characteristics and/or intended use of the AC disinfectant, either the first or second part, or both parts, may contain one or more optional ingredients such as skin conditioners, healing agents, surfactants, thickeners, builders, film-forming agents, and/or preservatives. Also, depending upon the two-part system, the AC disinfecting composition may be formed by simply mixing the first and second parts, often in approximately equal volumes, or may involve some additional dilution step before or after mixing.
Color has proved to be an important attribute for teat disinfectants, allowing farmers to visually confirm that the disinfectant has been properly applied to the teat. This is particularly advantageous for confirming application to large herds when multiple farm workers are applying the disinfectant to many different animals. Unfortunately, many such colorants used to impart the color are subject to chemical degradation upon formation of the AC disinfectant. Once the chlorite-containing part and acid part are combined, they form chlorous acid. Over time, the chlorous acid undergoes complex chemical transformations to form chlorine dioxide. Formation of too much chlorine dioxide is undesirable because chlorine dioxide is a gas in its natural state, which is noxious; chlorine dioxide can be corrosive to metal surfaces; and chlorine dioxide degrades colorants. Colorant degradation leads to ineffective coloration and teat marking as the disinfectant ages—that is, from the point in time following mixing of the first and second parts to form the AC disinfectant.
Teat disinfectants are generally considered animal “drugs” in most countries, and thus controlled by the regulatory agencies overseeing the same. Most often, the only colorants that can be used in a teat disinfectant are those dyes that have been approved for use in food and/or drugs. For example, in the United States approved dyes can be found in 21 C.F.R. §70.3. When present in an AC disinfectant, these dyes are susceptible to chemical oxidation and rapidly lose their color following formation of the disinfectant.
Previous attempts to address this problem have largely focused on use of pigments as opposed to dyes (see e.g., WO 99/16418, WO 99/16309 and EP 0 904 693 A1). Pigments are insoluble colorants and less susceptible to chemical degradation within the AC disinfectant. However, pigments are plagued by problems associated with settling out of solution, staining parlor floors, and clogging milk filters. In addition, such pigments are not approved in some countries for use in teat disinfectants since they are not approved for food or drug use by their regulatory agencies.
Accordingly, there remains a need in the art for improved AC disinfectants generally, as well as a need for controlling the formation of chlorine dioxide and consequently improving the color longevity of dyes within AC disinfectants, particularly those dyes that have been approved for use in food and drugs. The present invention fulfills these needs and provides further related advantages.